Load-lock technique

ABSTRACT

Disclosed is a load-lock system, an exposure apparatus having the same, and a load-lock method. In one preferred form, the load-lock system includes a chamber housing, and a capacity changing system for changing the capacity of the chamber housing. The load-lock method includes the steps of conveying an object into a chamber housing, reducing the capacity of the chamber housing after the conveying step, and reducing the pressure inside the chamber housing after the capacity reducing step.

FIELD OF THE INVENTION AND RELATED ART

This invention relates to load-lock technique applicable to productionof various microdevices such as, for example, semiconductor chips (e.g.,IC or LSI), display devices (e.g., liquid crystal panel), detectingelements (e.g., magnetic head), and image pickup devices (e.g., CCD).

The density and speed of a semiconductor integrated circuit have beenimproved significantly and, with this trend, the linewidth of anintegrated circuit pattern has been narrowed more and more. This forcesfurther improvements in the semiconductor manufacturing method. Asregards exposure apparatuses used for forming a resist pattern in alithographic process which is one of semiconductor manufacturingprocesses, those using deep ultraviolet light such as KrF laser light(wavelength 248 nm), ArF laser light (wavelength 193 nm) or F2 laserlight (wavelength 157 nm) have been developed. Currently, EUV exposureapparatuses that use extreme ultraviolet light (EUV light) of awavelength of about 10 nm, are being developed. Exposure apparatusesusing electron beam are being developed on the other hand.

If the wavelength is short such as EUV light, X-rays or electron beam,the exposure light is attenuated in the atmosphere. In consideration ofthis, to avoid attenuation of exposure light, the exposure process iscarried out in a vacuum ambience or a reduced pressure He ambience.

In process machines such as sputtering apparatus, carrying out a processin a vacuum ambience is common. Loading and unloading a substrate to beprocessed, from the atmosphere into a process chamber (vacuum ambience),is carried out by way of a load-lock chamber (housing).

In exposure apparatuses as well, load-lock chambers are used when asubstrate to be exposed is loaded into a vacuum ambience (exposureambience).

Referring now to FIG. 7, the structure of a known type load-lock systemwill be explained. Load-lock chamber (housing) 101 is provided at a sideof a main chamber 102 in which an exposure process is to be carried out.There is an atmosphere side gate valve 104 at one side of the load-lockchamber 101, and a vacuum side gate valve 103 at the other side of theload-lock chamber. For evacuation to create a vacuum level in thechamber, there are an exhaust pipe 105, an exhaust valve 106 and avacuum pump 107. Furthermore, for resuming an atmospheric pressureinside the chamber from the vacuum level, there are a gas supplying pipe108 and a gas supplying valve 109.

For loading a substrate 110 from the atmosphere into the main chamber102 which is in vacuum state, the vacuum side gate valve 103, theexhaust valve 106 and the gas supply valve 109 are kept closed and, onthe other hand, the atmosphere side gate valve 104 is opened. Then thesubstrate 110 is introduced into the chamber. Subsequently, theatmosphere side gate valve 104 is closed, and the exhaust valve 106 isopened. Normally, the vacuum pump 107 is kept driven uninterruptedly. Asregards the exhaust valve 106, generally, a butterfly valve is used. Byopening the exhaust valve 106, the atmospheric gas inside the load-lockchamber 101 is discharged outwardly. After the exhausting is completed,the exhaust valve 106 is closed and the vacuum side gate valve 103 isopened, and the substrate is introduced into the main chamber 102. Afterthe substrate is loaded, the vacuum side gate valve 103 is closed.

For unloading a processed substrate out of the main chamber 102, theload-lock chamber 101 is exhausted and placed in vacuum state (all thevalves and gate valves are kept closed), and thereafter the vacuum sidegate valve 103 is opened. Then, the substrate 110 is unloaded and movedback into the load-lock chamber 110. After this, the vacuum side gatevalve 103 is closed and, subsequently, the gas supply valve 109 isopened. The gas supply pipe 108 is communicated with the atmosphere,such that, by opening the gas supply valve 109, the inside of theload-lock chamber 101 can be filled with atmosphere. After anatmospheric pressure is reached, the atmosphere side gate valve 104 isopened, and the substrate 110 is moved outwardly.

With the procedure described above, it is assured that a substrate 110is conveyed between the atmosphere and the main chamber 102 withoutdamaging the vacuum state inside the main chamber 102.

In exposure apparatuses such as an X-ray exposure apparatus wherein theexposure is carried out in a reduced pressure He ambience, for loading asubstrate 110 into the main chamber 102, after the vacuum evacuation theload-lock chamber 101 is filled with He gas of a pressure similar tothat of the main chamber 102 and, subsequently, the vacuum side gatevalve 103 is opened and the substrate 110 is loaded.

Japanese Laid-Open Patent Applications, Publication Nos. 2001-102281,2003-031639, and 2003-045947 disclose examples of load-lock chamber thatcan be applied to a semiconductor exposure apparatus or the like.

However, in the load-lock chamber structure such as described above,when the gas is exhausted to create a vacuum level in place of theatmospheric pressure state, at the moment as the exhaust valve is openedthe atmospheric air inside the chamber is exhausted rapidly. This causesadiabatic expansion of the air and, thus, the temperature decreasessuddenly. As a result of this, the moisture content contained in theatmosphere is frozen and adhered to the substrate surface, causingcontamination of it. Simultaneously, since heat is carried away from thesubstrate, the temperature of the substrate is lowered. If the load-lockoperation and operations following it are carried out while thesubstrate temperature is low, the substrate temperature gradually risesin accordance with the surrounding temperature. Such temperature rise isa serious factor for slowing down the production yield, particularly ina process (such as lithographic process) where precise temperaturecontrol is required.

Generally, the inconveniences described above can be avoided by carryingout the vacuum exhausting slowly to provide a sufficient time fortransmission of heat between the air and the surrounding ambience.Load-lock systems are incorporated into process machines such as filmforming apparatus and, in such machines, the time required for theprocess itself is relatively long. Thus, there is a margin with respectto time that can be spent on substrate loading and unloading byload-locking. Even if the vacuum exhausting takes time, it does notaffect the throughput of the apparatus.

Among exposure apparatuses, those that are arranged to carry out theexposure process in a vacuum have already been used in practice such aselectron beam direct drawing apparatus, for example. Such apparatus havea very low throughput by nature, and the time necessary for loading andunloading a substrate by load-locking does not raise a problem. However,EUV exposure apparatuses and the like are machines designed for massproduction of MPUs or memories, for example, and a very high throughputof an order of 100 pieces per hour is required. If the load-lockstructure is arranged for slow exhausting, although the inconveniencessuch as substrate contamination or temperature decrease could be avoidedthereby, it needs a very long time for substrate loading and unloading.This is a serious factor for throughput decrease of the apparatus.Practically, therefore, the load-lock structure such as described abovecan not be applied to a machine such as EUV exposure apparatus in whicha large throughput is required.

SUMMARY OF THE INVENTION

It is accordingly an object of the present invention to provideload-lock technique by which high-speed vacuum exhausting is enabledwhile reducing or suppressing contamination or temperature decrease ofan object to be loaded and/or unloaded.

In accordance with an aspect of the present invention, there is provideda load-lock system, comprising: a chamber housing; and a capacitychanging system for changing the capacity of said chamber housing.

In accordance with another aspect of the present invention, there isprovided a load-lock method, comprising the steps of: conveying anobject into a chamber housing; reducing the capacity of the chamberhousing after said conveying step; and reducing the pressure inside thechamber housing after said capacity reducing step.

Briefly, in accordance with the present invention, load-lock techniqueby which high-speed pressure reduction is enabled while suppressingcontamination or temperature decrease of an object to be loaded and/orunloaded, can be provided.

These and other objects, features and advantages of the presentinvention will become more apparent upon a consideration of thefollowing description of the preferred embodiments of the presentinvention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view for explaining a load-lock system accordingto a first embodiment of the present invention.

FIG. 2A is a schematic view for explaining a state in which a substrateis loaded into a load-lock chamber, in the first embodiment of thepresent invention.

FIG. 2B is a schematic view for explaining a state in which a substratetable is raised, in the first embodiment of the present invention.

FIG. 2C is a schematic view for explaining a communicated state, in thefirst embodiment of the present invention.

FIG. 2D is a schematic view for explaining a state of loading asubstrate into a main chamber, in the first embodiment of the presentinvention.

FIG. 3A is a schematic view for explaining the communicated state priorto unloading of the substrate, in the first embodiment of the presentinvention.

FIG. 3B is a schematic view for explaining a state in which a substrateis unloaded and conveyed to the load-lock, in the first embodiment ofthe present invention.

FIG. 3C is a schematic view for explaining a state in which theload-lock is opened to the atmosphere, in the first embodiment of thepresent invention.

FIG. 3D is a schematic view for explaining a state in which a substrateconveyed outwardly to the atmosphere, in the first embodiment of thepresent invention.

FIG. 4 is a schematic view for explaining a load-lock system accordingto a second embodiment of the present invention.

FIG. 5A is a schematic view for explaining a state in which a substrateis loaded into a load-lock chamber, in the second embodiment of thepresent invention.

FIG. 5B is a schematic view for explaining a state in which a substratetable is raised, in the second embodiment of the present invention.

FIG. 5C is a schematic view for explaining a state of vacuum evacuation,in the second embodiment of the present invention.

FIG. 5D is a schematic view for explaining a state of loading asubstrate into a main chamber, in the second embodiment of the presentinvention.

FIG. 6 is a schematic view for explaining a state in which substrateconveyance has completed, in the second embodiment of the presentinvention.

FIG. 7 is a schematic view of a known type load-lock system.

FIG. 8 is a schematic view, showing an example of exposure apparatus.

FIG. 9 is a flow chart for explaining the procedure of devicemanufacturing processes.

FIGS. 10A and 10B are schematic views, respectively, for explaining thestructure of a third embodiment of the present invention.

FIG. 11 is a schematic view for explaining the structure of a caddyaccording to the present invention.

FIG. 12 is a schematic view for explaining the structure of a caddystation according to the present invention.

FIG. 13 is a schematic view for explaining the operation for storing awafer into a caddy of the present invention.

FIG. 14 is a schematic view for explaining the operation for loading acaddy of the present invention into a load-lock chamber 4.

FIG. 15 is a schematic view for explaining the structure of a fourthembodiment of the present invention.

FIG. 16 is a schematic view for explaining the operation for storing awafer into a caddy-like structure in the fourth embodiment of thepresent invention.

FIG. 17 is a schematic view for explaining the operation of a fifthembodiment of the present invention.

FIG. 18 is a schematic view for explaining another example of thestructure according to the fifth embodiment of the present invention.

FIG. 19 is a schematic view for explaining the operation of a sixthembodiment of the present invention.

FIG. 20 is a graph for explaining the relationship between a load-lockcapacity and a temperature decrease of a wafer.

FIGS. 21A and 21B are schematic views of known type structures.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of load-lock systems according to the presentinvention, specifically, embodiments wherein the invention is applied toan exposure apparatus, will now be described with reference to theattached drawings.

Embodiment 1

FIG. 1 illustrates a load-lock system according to a first embodiment ofthe present invention. In this embodiment, the invention is applied toan X-ray exposure apparatus in which the exposure process is carried outin a particular ambience such as reduced pressure He ambience, forexample. Denoted at 1 is a load-lock system of the present invention.The load-lock system 1 is provided to load a substrate 19 into a mainchamber 2 from the atmosphere and also to unload the substrate 19, afteran exposure process is carried out thereto inside the main chamber 2,outwardly (to the atmosphere), without breaking a particular ambience ofthe main chamber 2 such as reduced pressure He ambience, for example.Denoted at 2 is the main chamber in which a process (e.g., exposureprocess in this embodiment) is to be carried out to the substrate 19 ina particular ambience. Inside the main chamber 2, there are componentsfor carrying out an exposure process to the substrate 19, such as aconveyance robot, an original having a circuit pattern formed thereonand to be transferred to the substrate, a stage for aligning theoriginal and the substrate, and so on, although they are not illustratedin the drawing. Denoted at 3 is an ambience maintaining system formaintaining the exposure ambience, and it functions to keep a particularambience such as a reduced pressure He ambience of about 20 kPa, forexample.

The ambience maintaining system 3 maintains the pressure and purityinside the main chamber 2 by continuously supplying a high-purity He gaswhile exhausting excess He gas. Denoted at 32 is a measuring device formeasuring the total pressure and the He partial pressure, inside themain chamber 2. The He gas is supplied through a He supplying pipe 34.The pipe 34 is connected to a He reservoir (not shown), such that aconstant pressure He gas can be supplied continuously. Denoted at 33 isa He supply adjusting valve. By adjusting the degree of opening of thevalve 33, the inflow rate into the main chamber 2 can be adjusted.Denoted at 35 is a main chamber exhaust pipe which is connected to avacuum pump 37 through a main chamber exhaust adjusting valve 36. Byadjusting the degree of opening of the valve 36, the amount of gasexhaust from the main chamber 2 can be adjusted.

The values concerning the total pressure and the He partial pressureinside the main chamber 2, as measured by the measuring device 32, aretransmitted to a control system 31. On the basis of these values, thecontrol system 31 controls the degree of opening of the He supplyadjusting valve 33 and the main chamber exhaust adjusting valve 36, bywhich the He pressure and purity inside the main chamber 2 can bemaintained at constant levels.

The structure of the load-lock system 1 will be described below ingreater detail.

Denoted at 11 is a housing of a load-lock chamber (hereinafter, it maybe referred to simply as “load-lock chamber”) that is a major componentof the load-lock system 1, and it is a vacuum chamber. Denoted at 12 isa vacuum side gate valve that functions as a door between the mainchamber 2 and the load-lock chamber 11, for conveyance of the substrate19 therebetween. As this gate valve 12 is open, an opening is defined inthe side wall of the load-lock chamber 11 through which a substrate canbe conveyed. As the gate valve 12 is closed, the chamber can begas-tightly closed. Denoted at 13 is an atmosphere side gate valve, andit serves as a door between the load-lock chamber 11 and the atmosphere(outside the apparatus or an ambience different from that of theexposure apparatus), for conveyance of the substrate 19 between them.When the gate valve 13 is open, an opening is defined in the side wallof the load-lock chamber 11. When it is closed, on the other hand, theload-locking wall surface is gas-tightly closed.

Denoted at 14 is a gas supply pipe for supplying a gas into theload-lock chamber 11. There is a gas supply valve 15 for supplying a gasand for stopping the gas supply. In this example, the tip end of thepipe 14 is open to the atmosphere, and the gas supplied into theload-lock chamber 11 is an air. However, the pipe 14 may be connected toa gas supply line so that any desired gases appropriate to the workingcondition, such as dry air or dry nitrogen, for example, may be used. Inthis example, the pipe 14 serves to supply a gas (atmosphere) into theload-lock chamber 11 in vacuum state when the substrate 19 is to beunloaded outwardly of the apparatus, thereby to remove a differentialpressure between the atmosphere and the load-lock chamber 11 and toallow opening of the atmosphere side gate valve 13. This is because,generally, a gate valve is inoperative if there is a differentialpressure as in a case where an atmospheric pressure is being appliedonly at one side. Denoted at 16 is a communication pipe forcommunicating the inside of the main chamber 2 and the inside of theload-lock chamber 11 with each other. The state of communication can becontrolled by opening/closing a communication valve 17 provided in aportion of the pipe. The functions of these communication pipe 16 andcommunication valve 17 will be explained later.

Denoted at 21 is a substrate table which constitutes a portion of theload-lock chamber housing 11. This is a table on which a substrate 19 isto be loaded, inside the load-lock chamber 11. The substrate table 21has three pins. Since the contact to the substrate 19 is limited tothese three points, contamination of the substrate due to adhesion ofparticles can be suppressed to a lowest level. The substrate table 21 ismounted on a driving unit 22 through an arm 32 having high rigidity. Thedriving unit 22 is operable to move the arm 23 and the substrate table21 integrally, upwardly and downwardly. Regarding the driving method, itmay be a combination of a ball screw and a straight guide, for example.Denoted at 20 is a vacuum seal provided around the circumference of theside face of the substrate table 21. The seal 20 is slidable between thesubstrate table and the inner wall of the load-lock chamber 11, and ithas a vacuum locking function. In this example, the seal 20 is a sealmember such as O-ring, for example. However, a labyrinth structure maybe used and, by differential exhausting, vacuum locking may beaccomplished. Alternatively, a bellows structure may be used.

By moving the substrate table 21 upwardly or downwardly through thedriving unit 22, the inside volume or capacity of the load-lock chamber11 into which the substrate 19 is to be mounted can be changed.

Denoted at 18 is a door opening to the atmosphere, which is provided atthe ceiling of the load-lock chamber 11. This door is provided to definean opening, as the substrate table 21 is raised, for exhausting theinside gas (air) of the load-lock chamber 11 outwardly. If isolationfrom the atmosphere is necessary, the door 18 is closed and vacuumlocking is accomplished. The opening of the door 18 should besufficiently wide to avoid that the gas (air) is compressed as thesubstrate table 21 is raised. For this reason, the door 18 shoulddesirably have a gate valve structure used for loading/unloading thesubstrate 19. A filter (not shown) may be provided at the top of thedoor 18, to prevent particles from entering the load-lock chamber 11.

The operation of the load-lock system 1 will now be described insequence.

Initially, the sequence for conveying a substrate from the atmosphereinto the main chamber 2 of reduced pressure He ambience, will beexplained. Initial state is that the atmosphere side gate valve 13 isopen while the remaining valves are closed, and the substrate table 21is at its lowered position. From this initial state, a substrate 19 isconveyed out of a substrate cassette in the atmosphere up to thesubstrate table 21 inside the load-lock chamber 11. The substrate 21 isin the lowered state. When the substrate table 21 is lowered, asufficient space for loading the substrate into the load-lock chamber 11is obtainable. After the substrate 19 is conveyed onto the substratetable 21, the door 18 opening to the atmosphere is opened. FIG. 2A showsthis state.

Subsequently, the atmosphere side gate valve 13 is closed and thedriving unit 22 is actuated to raise the substrate table 21. At thistime, the airs inside the load-lock chamber 11 are pushed and dischargedoutwardly through the opening of the door 18. FIG. 2B shows the state inwhich the substrate table 21 has been raised.

After the table 21 is raised, the door 18 is closed. When the table 21is at its raised position, the inside volume of the load-lock chamber issmallest, and only a few air remains there. After this, thecommunication valve 17 is opened to bring the load-lock chamber 11 andthe main chamber 2 in communication with each other. Although a verysmall amount of air flows into the main chamber 2 from the load-lockchamber 11, the pressure is instantaneously balanced, and the load-lockchamber 11 and the main chamber 2 have the same ambience. FIG. 2C showsthis state. As the air flows into the main chamber 2, the He purity andthe pressure inside the main chamber 2 will change. However, by makingthe inside capacity of the load-lock chamber 11 as the substrate table21 is in its raised position very small as compared with the capacity ofthe main chamber, such change can be made small within an allowablerange. The ambience of the main chamber 2 having its pressure and Hepurity changed by a small amount, can resume its original conditionshortly with the aid of the ambience maintaining system 3.

After the communication valve 17 is opened, the vacuum side gate valve12 is opened. At the same time, the substrate table 21 is lowered. FIG.2D shows this state. As the substrate table 21 is lowered, the totalvolume of the reduced pressure He gas increases. Here, the controlsystem 31 inside the ambience maintaining unit 3 operates to increasethe He injection amount in accordance with changes in the He gaspressure and, therefore, the He gas pressure can be kept constant.

As the table 21 is lowered, a sufficient space for conveyance of thesubstrate 19 is assured. Thus, by means of a conveyance robot (notshown) inside the main chamber 2, the substrate 19 is conveyed to anexposure position inside the main chamber 2.

With the procedure described above, substrate conveyance from theatmosphere into the main chamber having a reduced pressure He ambienceis completed.

Next, the sequence of conveying a substrate from the main chamber 2 intothe atmosphere will be explained.

The state just before initiation of the substrate unloading is that theatmosphere side gate valve 13, the vacuum side gate valve 12, the gassupply valve 15 and the communication valve 17 are all closed.

Initially, the communication valve 17 is opened to provide the sameambience in the load-lock chamber 11 and the main chamber 2 (FIG. 3A).Subsequently, the vacuum side gate valve 12 is opened and,simultaneously therewith, the driving unit 22 drives the substrate table21 to move it downwardly to secure a sufficient space. Thereafter, bymeans of a conveyance robot (not shown), the substrate 19 is unloadedand placed onto the substrate table 21 from the main chamber 2 (FIG.3B).

After this, the vacuum side gate valve 12 is closed. After the valve isclosed, the gas supply valve 15 is opened and the inside of theload-lock chamber 11 is filled with atmosphere. Then, the door 18 isopened, and the substrate table 21 is lowered (FIG. 3C). Since the door18 is open, as the table 21 is lowered, the atmosphere can flow into theload-lock chamber 11 without resistance.

Then, the atmosphere side gate valve 13 is opened, and the substrate 19is unloaded by a conveyance robot (not shown) outwardly of the load-lockchamber 11 (FIG. 3D).

With the procedure described above, conveyance of the substrate from themain chamber into the atmosphere is completed.

In conventional load-lock systems, for loading a substrate, the insideof the load-lock chamber has to be once vacuum evacuated. In order toavoid freezing of moisture content due to adiabatic expansion of the airduring the exhaust and resultant temperature decrease of the substrateas well, the exhausting operation should be done slowly while spending along time.

As compared therewith, in the load-lock system 1 of the X-ray exposureapparatus according to this embodiment, there is no process in thesubstrate loading that involves adiabatic expansion of an air. Hence,there is no possibility of freezing of moisture content or temperaturedecrease of the substrate, and high-speed substrate conveyance can beaccomplished. Furthermore, use of an exhaust pump for load-locking isunnecessary, and this effectively decreases the cost of the apparatus.

In this embodiment, various valves are controlled by control means suchas a microcomputer provided inside the apparatus, and they can beactuated automatically.

As regards the door 18 opening to the atmosphere, it is not alwaysnecessary to provide the same at the ceiling. It may be provided at aside wall, near the ceiling. Alternatively, the atmosphere side gatevalve 13 may be used also as the door opening to the atmosphere.

Embodiment 2

FIG. 4 illustrates a load-lock system according to a second embodimentof the present invention. In this embodiment, the invention is appliedto an EUV exposure apparatus in which the exposure process is carriedout in a vacuum ambience. In this embodiment, components havingcorresponding functions as of those of the first embodiment are denotedby like numerals, and detailed description for them will be omitted.

Denoted at 1 is a load-lock system of the present invention. Theload-lock system 1 is provided to load a substrate 19 into a mainchamber 2 from the atmosphere and also to unload the substrate, after anexposure process is carried out thereto inside the main chamber 2,outwardly (to the atmosphere), without breaking a vacuum ambience of themain chamber 2. Denoted at 2 is the main chamber which is normallyexhausted by means of a vacuum pump, and a vacuum level is maintainedtherein. Inside the main chamber 2, there are components for carryingout an exposure process to the substrate 19, such as a conveyance robot,an original having a circuit pattern formed thereon and to betransferred to the substrate, a stage for aligning the original and thesubstrate, and so on, although they are not illustrated in the drawing.

The structure of the load-lock system 1 will be described below ingreater detail.

Denoted at 11 is a load-lock chamber (housing) that is a major componentof the load-lock system 1, and it is a vacuum chamber. Denoted at 12 isa vacuum side gate valve that functions as a door for conveyance of thesubstrate 19 between the main chamber 2 and the load-lock chamber 11.Denoted at 13 is an atmosphere side gate valve, and it serves as a doorbetween the load-lock chamber 11 and the atmosphere side (outside theapparatus), for conveyance of the substrate 19 between them. Denoted at14 is a gas supply pipe for supplying a gas into the load-lock chamber11. There is a gas supply valve 15, provided in a portion of the gassupply pipe 14. In this example, the tip end of the pipe 14 is open tothe atmosphere, and the gas supplied into the load-lock chamber 11 is anair. However, the pipe 14 may be connected to a gas supply line so thatdry air or dry nitrogen, for example, may be supplied.

Denoted at 41 is a vacuum gauge for measuring the pressure (vacuumlevel) inside the load-lock chamber 11. Denoted at 42 is an exhaust pipewhich is connected to a load-lock exhaust pump 44 via an exhaust valve43 provided in a portion of the exhaust pipe. The exhaust pump 44 isnormally operated and, when the exhaust valve 43 is open, it functionsto perform vacuum evacuation of the load-lock chamber 11.

Denoted at 21 is a substrate table. This is a table on which a substrate19 is to be loaded, inside the load-lock chamber 11. The substrate table21 has three pins. Since the contact to the substrate 19 is limited tothese three points, contamination of the substrate due to adhesion ofparticles can be suppressed to a lowest level. The substrate table 21 ismounted on a driving unit 22 through an arm 32 having high rigidity. Thedriving unit 22 is operable to move the arm 23 and the substrate table21 integrally, upwardly and downwardly. Regarding the driving method, itmay be a combination of a ball screw and a straight guide, for example.Denoted at 20 is a vacuum seal provided around the circumference of theside face of the substrate table 21. The seal 20 is slidable between thesubstrate table and the inner wall of the load-lock chamber 11, and ithas a vacuum locking function. In this example, the seal 20 is a sealmember such as O-ring, for example. However, a labyrinth structure maybe used and, by differential exhausting, vacuum locking may beaccomplished. Alternatively, a bellows structure may be used.

By moving the substrate table 21 upwardly or downwardly through thedriving unit 22, the inside volume or capacity of the load-lock chamber11 into which the substrate 19 is to be mounted can be changed.

Denoted at 18 is a door opening to the atmosphere, which is provided atthe ceiling of the load-lock chamber 11. This door is provided to definean opening, as the substrate table 21 is raised, for exhausting theinside gas (air) of the load-lock chamber 11 outwardly. If the load-lockchamber is to be exhausted, for example, the door 18 is closed andvacuum locking is accomplished. The opening of the door 18 should besufficiently wide to avoid that the gas (air) is compressed as thesubstrate table 21 is raised. For this reason, the door 18 shoulddesirably have a gate valve structure used for loading/unloading thesubstrate 19. A filter (not shown) may be provided at the top of thedoor 18, to prevent particles from entering the load-lock chamber 11.

The operation of the load-lock system 1 will now be described insequence.

Initial state is that the atmosphere side gate valve 13 is open whilethe remaining valves are closed, and the substrate table 21 is at itslowered position. FIG. 5A shows the state in which, from this initialstate, a substrate 19 is conveyed out of a substrate cassette in theatmosphere up to the substrate table 21 inside the load-lock chamber 11.Here, the substrate 21 is in the lowered state. When the substrate table21 is lowered, a sufficient space for loading the substrate into theload-lock chamber 11 is obtainable. After the substrate 19 is conveyedonto the substrate table 21, the door 18 opening to the atmosphere isopened.

At the same time as the door 18 is opened, the driving unit 22 isactuated to raise the substrate table 21. The air inside the load-lockchamber 11 is pushed outwardly through the opening of the door 18.

Thereafter, the door 18 and the atmosphere side gate valve 13 areclosed. FIG. 5B shows this state. As the substrate table 21 is at araised position, the capacity of the load-lock chamber 11 is smallest,and only a small amount air remains there. From this state, the exhaustvalve 43 is opened, and the air inside the load-lock chamber 11 isexhausted. For reasons to be described later, the exhaust valve 43 maybe fully opened at once. FIG. 5C shows the state in which vacuumevacuation is carried out.

In conventional load-lock systems as described hereinbefore, ifexhausting is carried out rapidly, due to adiabatic expansion of theair, moisture content in the air will freeze to contaminate thesubstrate, or the substrate temperature decreases undesirably.Therefore, in conventional load-lock systems, it is necessary to controlthe degree of opening of the exhaust valve to carry out the vacuumevacuation slowly. In the load-lock system 1 of this embodiment, ascompared therewith, since only a limited amount of air remains insidethe load-lock chamber 1, even if the exhausting is made at high speed,freezing of moisture content and a decrease of substrate temperature canbe well suppressed.

Because the gas to be exhausted is little, as the exhaust valve 43 isopened, high vacuum is created inside the load-lock chamber 11 in a veryshort time. The vacuum level inside the load-lock chamber 11 ismonitored by the vacuum gauge 41, and if a predetermined level isreached, the exhaust valve 43 is closed.

After the valve 43 is closed, the vacuum side gate valve 12 is openedand, simultaneously therewith, the driving unit 22 is actuated to movethe substrate table 21 downwardly. When the table 21 is lowered, sinceboth of the inside of the load-lock chamber 11 and the inside of themain chamber 2 are already in vacuum state, no problem arises even ifthe volume changes. FIG. 5D shows the state in which the substrate table21 has moved downwardly. After the table 21 is lowered, the substrate 19is conveyed by a conveyance robot (not shown) to an exposure positioninside the main chamber 2, for example.

With the procedure described above, conveyance of the substrate 19 fromthe atmosphere into the main chamber 2 of vacuum ambience is completed.After the conveyance, the vacuum side gate valve 12 is closed (FIG. 6).

The sequence of unloading the substrate from the main chamber 2 back tothe atmosphere is essentially the same as that of the conventionalload-lock system, and description thereof will be omitted. This would bereadily understood from the fact that the state shown in FIG. 6 issimilar to that of FIG. 7 having been described with reference to theconventional example.

In accordance with the load-lock chamber 11 of this embodiment, thevolume is made changeable and, by doing so, the space for substrateconveyance is secured on one hand and, since the volume of gas to beexhausted is made small, high-speed evacuation is enabled on the otherhand.

In this embodiment, various valves are controlled by control means suchas a microcomputer provided inside the apparatus, and they can beactuated automatically.

As regards the door 18 opening to the atmosphere, it is not alwaysnecessary to provide the same at the ceiling. It may be provided at aside wall, near the ceiling. Alternatively, the atmosphere side gatevalve 13 may be used also as the door opening to the atmosphere.

FIG. 8 shows an exposure apparatus for device manufacture, to which aload-lock system as described hereinbefore is incorporated.

This exposure apparatus is to be used for manufacture of microdeviceshaving a fine pattern formed thereon, such as semiconductor devices(semiconductor integrated circuits, for example), micromachines, orthin-film magnetic heads, for example. In this exposure apparatus,exposure light (which may include visible light, ultraviolet light, EUVlight, X-ray, electron beam, and charged particle beam, for example) asan exposure energy supplied from a light source 161 illuminates areticle R (original), and light from the reticle R is projected onto asemiconductor wafer W (substrate) through a projection system having aprojection lens 162 (which may include refractive lens, reflective lens,catadioptric lens system, and charged particle lens, for example),whereby a desired pattern is produced on the substrate.

The exposure apparatus includes a base table 151 having a guide 152 anda linear motor stator 121 fixed thereto. The linear motor stator 121 hasa multiple-phase electromagnetic coil, while a linear motor movableelement 111 includes a permanent magnet group. The linear motor movableportion 111 is connected as a movable portion 153 to a movable guide 154(stage), and through the drive of the linear motor M1, the movable guide154 can be moved in a direction of a normal to the sheet of the drawing.The movable portion 153 is supported by a static bearing 155, taking theupper surface of the base table 151 as a reference, and also by a staticbearing 156, taking the side surface of the guide 152 as a reference.

A movable stage 157 which is a stage member disposed to straddle themovable guide 154 is supported by a static bearing 158. This movablestage 157 is driven by a similar linear motor M2, so that the movablestage 157 moves leftwardly and rightwardly as viewed in the drawing,while taking the movable guide 154 as a reference. The motion of themovable stage 157 is measured by means of an interferometer 160 and amirror 59 which is fixed to the movable stage 159.

A wafer (substrate) W is held on a chuck which is mounted on the movablestage 157, and a pattern of the reticle R is transferred in a reducedscale onto different regions on the wafer W by means of the light source161 and the projection optical system 162, in accordance with astep-and-repeat method or a step-and-scan method.

It should be noted that the load-lock system of the present inventiondescribed hereinbefore can be similarly applied also to an exposureapparatus in which, without using a mask, a circuit pattern is directlydrawn on a semiconductor wafer to expose a resist thereon.

Next, an embodiment of a device manufacturing method which uses anexposure apparatus described above, will be explained.

FIG. 9 is a flow chart for explaining the overall procedure forsemiconductor manufacture. Step 1 is a design process for designing acircuit of a semiconductor device. Step 2 is a process for making a maskon the basis of the circuit pattern design. Step 3 is a process forpreparing a wafer by using a material such as silicon. Step 4 is a waferprocess which is called a pre-process wherein, by using the thusprepared mask and wafer, a circuit is formed on the wafer in practice,in accordance with lithography. Step 5 subsequent to this is anassembling step which is called a post-process wherein the wafer havingbeen processed at step 4 is formed into semiconductor chips. This stepincludes an assembling (dicing and bonding) process and a packaging(chip sealing) process. Step 6 is an inspection step wherein anoperation check, a durability check an so on, for the semiconductordevices produced by step 5, are carried out. With these processes,semiconductor devices are produced, and they are shipped (step 7).

More specifically, the wafer process at step 4 described above includes:(i) an oxidation process for oxidizing the surface of a wafer; (ii) aCVD process for forming an insulating film on the wafer surface; (iii)an electrode forming process for forming electrodes upon the wafer byvapor deposition; (iv) an ion implanting process for implanting ions tothe wafer; (v) a resist process for applying a resist (photosensitivematerial) to the wafer; (vi) an exposure process for printing, byexposure, the circuit pattern of the mask on the wafer through theexposure apparatus described above; (vii) a developing process fordeveloping the exposed wafer; (viii) an etching process for removingportions other than the developed resist image; and (ix) a resistseparation process for separating the resist material remaining on thewafer after being subjected to the etching process. By repeating theseprocesses, circuit patterns are superposedly formed on the wafer.

Next, another aspect of the present invention will be described.

The density of a semiconductor device has been improved significantly,and the size and linewidth of a semiconductor integrated circuit hasbeen narrowed more and more.

Regarding semiconductor exposure apparatuses for transferring a circuitpattern onto a silicon wafer, for miniaturization of the pattern, thewavelength of exposure light used for the exposure process has to beshortened. Hence, the wavelength has been shortened such as from g-lineor i-line to KrF, ArF, F2 laser and soft X-rays emitted from an SR(synchrotron radiation) ring.

Short-wavelength exposure light is attenuated largely in the atmosphere.Therefore, the exposure unit of an exposure apparatus is accommodated ina chamber, and the chamber interior is filled with a reduced pressure Heambience or a vacuum ambience in which attenuation of exposure light issmall.

In process machines, on the other hand, where a process gas is differentfrom the atmosphere or for prevention of oxidation of a resist on awafer, an ambience different from the atmosphere or a vacuum ambience isused.

In such process machines, for conveyance of a substrate between achamber (first process chamber) having a process station therein and asubstrate supply station disposed in the atmosphere, a load-lock chamber(second process chamber) is used. The substrate to be processed may beSi wafer or reticle. There are cases wherein a plurality of load-lockchambers are provided, for substrate loading and unloading.

Here, referring to FIGS. 21A and 21B, an example of known type processmachine having a load-lock chamber 4 will be explained.

In the process machine illustrated, a process chamber having a substrateprocess station therein is filled with a reduced pressure He ambience.

In the atmosphere, there is a wafer carrier mounting portion (wafersupply unit) 3. Also, in the atmosphere, there is a first wafer carrierconveying means 51 which is able to access the carrier mounting portion3 and the load-lock chamber 4.

The load-lock chamber 4 has a first gate valve 41 for intercepting thesame from the wafer supply unit 3, a second gate valve 42 forintercepting the same from the process chamber, exhaust means (notshown) for exhausting the inside of the load-lock chamber 4, and gassupply means (not shown) for supplying He or N2.

Additionally, the load-lock chamber 4 has a wafer mounting table whichis arranged to accommodate therein one or more wafers.

The operation of this known type load-lock system will be explainedbelow.

Initially, first conveying means 51 takes one wafer out of a wafercarrier mounted in the wafer carrier mounting portion 3, and it conveysthe wafer into the load-lock chamber 4.

As the wafer is conveyed into the load-lock chamber 4 and is placed onthe wafer mounting table, the first gate valve 41 is closed to interceptthe chamber from the atmosphere, and then replacement of the insideambience of the load-lock chamber 4 is carried out.

The inside ambience of the load-lock chamber 4 is carried out asfollows.

As the first gate valve 41 is closed and the load-lock chamber isisolated from the atmosphere and the process chamber, a vacuum exhaustvalve (not shown) is opened. Then, through a vacuum exhaust pipe and bymeans of a vacuum pump (not shown), the gas inside the load-lock chamber4 is exhausted.

Vacuum evacuation is carried out until a predetermined vacuum level isreached. After the exhausting is carried out and the predeterminedvacuum level is reached, the vacuum exhaust valve is closed and vacuumevacuation is interrupted.

Subsequently, a gas supply valve (not shown) is opened. The load-locksystem shown in the drawing is provided with a He gas supplying valveand an N2 gas supplying valve. The valve opened here is the valve forsupplying the same gas as the chamber ambience in which a processchamber is accommodated. Hence, the He gas supplying valve is opened.

The He gas is supplied until the pressure inside the load-lock chamber 4becomes equal to the pressure inside the process chamber. As thepressure inside the load-lock chamber 4 becomes equal to the pressureinside the process chamber, the He gas supply valve is closed and thesupply of He gas is turned off.

As the He gas supply is stopped, the second gate valve 42 is opened, andthe wafer inside the process chamber is unloaded therefrom by secondconveying means 52. The wafer is conveyed to a process station (notshown).

The wafer having been processed at the process station is conveyed bythe second conveying means 52 and the first conveying means 51 by way ofthe load-lock chamber 4, and it is moved back into the wafer carrier 3.

Since the inside volume of the load-lock chamber 4 is constant, when theload-lock chamber 4 is evacuated, the gas inside the chamber causesadiabatic expansion and the temperature thereof decreases. Although itdepends on various factors including the exhaust, the temperaturedecrease of the inside gas may be more than a few degrees and, dependingon the condition, the temperature may decrease beyond the freezingpoint.

Since the substrate placed inside the load-lock chamber 4 is exposed tothe gas inside the chamber, its temperature is lowered together with thecooling of the gas.

The substrate whose temperature has decreased with the adiabaticexpansion inside the load-lock chamber 4 is loaded into the apparatus inresponse to the completion of ambience replacement.

In the exposure apparatus, the temperature of a substrate must becontrolled precisely to keep the transfer precision, linewidth precisionand so on. However, the substrate conveyed through the load-lock chamber4 has its temperature decreased as described above and, therefore, ifthe substrate is exposed in this state, it directly causes degradationof the transfer precision.

Conventionally, for controlling the wafer temperature at a predeterminedtemperature, it is an example to wait for that the substrate temperaturegradually comes up to and becomes equal to a predetermined temperatureas the wafer contacts an ambient gas or substrate conveying means.

Another example is to provide a heater or any other heating means insidethe apparatus to heat the substrate, thereby to prevent temperaturedecrease of the substrate due to adiabatic expansion. There is variationwith respect to the location where the heater or heating means isprovided, such as in the atmosphere, the load-lock chamber, the processchamber and the like.

The former example is a simple method with respect to the apparatusstructure. However, it takes a long time until a predetermined substratetemperature is reached, and the throughput is lowered undesirably.

The latter example has inconveniences such as that the apparatusstructure is complicated due to the addition of heating means, thatcomplicated control is necessary, and that heat from the heating meansis transmitted to the apparatus to cause local deformation and, thus,degradation of the substrate conveyance precision.

Temperature decrease of the gas and resultant temperature decrease ofthe substrate can be suppressed by slowing down the vacuum evacuation ofthe load-lock chamber 4.

More specifically, usually the wall of the load-lock chamber 4 is madeof metal, and it has a large heat capacity with regard to a wafer or agas. Furthermore, since the outer wall of the load-lock chamber 4 is incontact with the atmosphere, even if the temperature is lowered, heat isapplied from the atmosphere. Thus, it causes less temperature decrease.In other words, it is an equivalent to having a very large heatcapacity.

The gas inside the load-lock chamber 4 is continuously in contact withthe wall surface of the load-lock chamber. If the temperature of the gasis lower than the wall surface temperature, heat is applied to the gasfrom the wall surface. Furthermore, in addition to heat application dueto direct contact, the gas receives heat by radiation from the wallsurface. For this reason, if the vacuum evacuation is carried outslowly, the time in which the gas receives heat from the wall isprolonged, such that the total amount of heat received from the wallbecomes large. Thus, there is an advantage of less temperature decreaseof the gas.

With this method, however, the time for vacuum evacuation has to be setextraordinarily long, and this causes a considerable decrease of thethroughput.

As described above, in regard to the problem of temperature decrease ofthe substrate resulting from adiabatic expansion of the gas inside theload-lock chamber during vacuum evacuation, conventionally adoptedmethods in turn cause different inconveniences such as decreasedthroughput, complicatedness of the structure, degraded substrateconveyance precision and so on.

It is an object of the present invention in another aspect thereof toprovide a substrate processing machine by which, in regard to atemperature decrease of a substrate due to adiabatic expansion inside aload-lock chamber during vacuum evacuation of the same, the insidevolume of the load-lock chamber is maintained not greater than 20 timesthe volume of the substrate. With this arrangement, the temperaturedecrease of the substrate can be held not greater than 0.3° C. and,thus, a process such as an exposure process can be carried out to thesubstrate promptly after the substrate is loaded into a process chamber.An improved throughput is attainable thereby.

In accordance with one preferred form of the present invention, to solveat least one of the inconveniences described above, the inside volume ofa load-lock chamber is set approximately not greater than 10 times thevolume of the substrate to be conveyed through the load-lock chamber.

In accordance with another aspect of the present invention, a holder aswell is introduced into a load-lock chamber 4 together with a substrate.With the volume of this holder, an effect being equivalent to reducingthe inside capacity of the load-lock chamber is obtainable and, on thebasis of it, the capacity of the load-lock chamber can be madeapproximately not greater than 10 times the volume of the substrate.

In accordance with another aspect of the present invention, the insidecapacity of the load-lock chamber is made changeable and, after asubstrate is loaded into the load-lock chamber, the capacity of theload-lock chamber is reduced thereby to assure that the inside capacityof the load-lock chamber is approximately not greater than 10 times thevolume of the substrate.

The capacity of the load-lock chamber has a relation with thetemperature decrease of the substrate inside the load-lock chamber 4.The smaller the capacity of the load-lock chamber is, the smaller thetemperature decrease is.

For a load-lock chamber that accommodates a wafer of 300 mm therein, forexample, it should have a floor area of about 320(mm)×320(mm)=102,400mm². Based on this, calculations were made on the temperature decreaseof a 300 mm wafer while changing the height of the load-lock chamber.The graph of FIG. 20 shows the results. In the calculation, the timerequired for exhausting was assumed as constant.

A steeply increasing curve is the inner surface area of the chamber, andit is proportional to the load-lock capacity with a certain offset. Onthe other hand, the wafer temperature and the gas temperature inside theload-lock chamber are normally at 23° C., and they decrease with thecapacity. Namely, the larger the load-lock chamber capacity is, thelarger the temperature decrease is.

As far as the adiabatic expansion which is a peculiar physicalphenomenon concerns, the lowest gas temperature is determined only bythe initial pressure and the final pressure independently of thecapacity of the load-lock chamber or the like. In practicalload-locking, however, the gas inside the load-lock is in contact withthe wall of the load-lock chamber and the gas receives heat by contact.Generally, the load-lock chamber is made of metal, and the metal itselfhas a large heat capacity as compared with the inside gas. Furthermore,the wall of the load-lock chamber is in contact with atmosphere and, inthis respect, it is equivalent to that the chamber has a very large heatcapacity as compared with the gas inside the chamber. For these reasons,the gas inside the load-lock chamber causes temperature decrease due toadiabatic expansion and, on the other hand, it receives heat from theload-lock chamber. The amount of heat to be received is proportional tothe contact area and, hence, the larger the inner surface area of theload-lock chamber is, the larger the amount of heat received is.

However, if the floor area is taken as constant as described above, itis seen that the rate of change in the increase of chamber capacity islarger than that of the increase of area. This means that the increaseof gas capacity is larger in proportion than the increase of heatquantity received. Hence, the smaller the load-lock chamber capacity is,the smaller the temperature decrease of the gas is.

A wafer is exposed to gas inside the load-lock chamber. Therefore, ifthe gas temperature decreases, the wafer is cooled thereby and itstemperature is lowered. Thus, a temperature decrease of the gas causes atemperature decrease of the wafer.

Where an electrostatic chuck is used as a substrate holding unit of asubstrate processing station, the temperature of the substrate when itis attracted to the chuck should be maintained in a range of 0.19° C.,in terms of the temperature difference with the chuck. In order to keepthe substrate temperature decrease not greater than 0.19° C., it is seenfrom FIG. 20 that the capacity of the load-lock chamber 4 should be 0.5L. Since the size in thickness direction is 5 mm and the volume is about55,000 mm in the case of a 300 mm wafer, the load-lock chamber volume of0.5 L means that, in terms of the substrate volume, the load-lockchamber volume should well be made approximately not greater than 10times the substrate volume.

In other words, by making the load-lock chamber capacity about 10 timeslarger than the substrate volume, the temperature decrease of thesubstrate when the load-lock chamber 4 is vacuum evacuated can be madenot greater than 0.19° C. Thus, the inconveniences of substratetemperature decrease involved in the vacuum evacuation of the load-lockchamber can be solved without raising additional problems.

With the arrangement described above, a wafer loaded into the apparatusfrom the load-lock chamber is at a desired temperature at the moment asthe same is loaded. Hence, a process such as exposure process can bedone promptly after the loading and, thus, the precision and throughputas well are improved.

The present invention can be embodied in various forms. Examples can besummarized as follows.

(1) A reduced- or normal-pressure substrate processing apparatuscomprising a first process chamber for performing a process in anambience different from an atmosphere, and a second process chamberconnected to the first process chamber and the atmosphere, respectively,through an opening/closing mechanism, wherein a substrate which is anobject to be processed is going to be conveyed from the atmosphere tothe first process chamber through the second process chamber, andwherein the second process chamber has an inside capacity which isapproximately not greater than 10 times the volume of the substrateconveyed through the second process chamber.

(2) A reduced- or normal-pressure substrate processing apparatuscomprising a first process chamber for performing a process in anambience different from an atmosphere, and a second process chamberconnected to the first process chamber and the atmosphere, respectively,through an opening/closihg mechanism, wherein a substrate which is anobject to be processed is going to be conveyed from the atmosphere tothe first process chamber through the second process chamber, whereinthe substrate is stored into a container as the same is in theatmosphere, wherein the container is sealingly closed in the atmosphere,wherein the container is conveyed to the first process chamber throughthe second process chamber, and wherein the capacity of the space insidethe second process chamber as the container is being placed inside thesecond process chamber is made approximately not greater than 10 timesthe volume of the substrate conveyed.

(3) A reduced- or normal-pressure substrate processing apparatuscomprising a first process chamber for performing a process in anambience different from an atmosphere, and a second process chamberconnected to the first process chamber and the atmosphere, respectively,through an opening/closing mechanism, wherein a substrate which is anobject to be processed is going to be conveyed from the atmosphere tothe first process chamber through the second process chamber, wherein asubstrate storing container is provided while being movable into thesecond process chamber, wherein the substrate is stored into thecontainer as the same is in the atmosphere, wherein the container issealingly closed in the atmosphere, wherein the container is placed intothe second process chamber and then the atmospheric ambience of thesecond process chamber is replaced by an ambience the same as that ofthe first process chamber, wherein the container is moved into the firstprocess chamber and the substrate is then taken out of the container andconveyed to the first process chamber, and wherein the capacity of thespace inside the second process chamber as the container is being placedinside the second process chamber is made approximately not greater than10 times the volume of the substrate conveyed.

(4) A reduced- or normal-pressure substrate processing apparatuscomprising a first process chamber for performing a process in anambience different from an atmosphere, and a second process chamberconnected to the first process chamber and the atmosphere, respectively,through an opening/closing mechanism, wherein a substrate which is anobject to be processed is going to be conveyed from the atmosphere tothe first process chamber through the second process chamber, whereinthe second process chamber is arranged to provide a variable capacity,and wherein the capacity of the second process chamber as the substrateis being placed therein is changeable to assure that the capacity of thesecond process chamber is approximately not greater than 10 times thevolume of the substrate conveyed.

(5) A substrate processing apparatus comprising a first process chamberfor performing a process to an object to be processed, in an ambiencedifferent from an atmosphere, a second process chamber connected to thefirst process chamber and the atmosphere, respectively, through anopening/closing mechanism, and conveying means for conveying the objectfrom the atmosphere to the first process chamber through the secondprocess chamber, wherein the capacity of the second process chamber isapproximately not greater than 10 times the volume of the object.

(6) An exposure apparatus including a substrate processing apparatus asrecited in any one of Items (1) to (5) above.

(7) An exposure apparatus including a substrate processing apparatus asrecited in any one of Items (1) to (5) above, and an optical system fordirecting light from a light source to the object to be processed.

(8) A device manufacturing method comprising the steps of exposing anobject to be processed, by use of an exposure apparatus as recited inItem (6) or (7), and developing the exposed object.

As regards the temperature decrease of the substrate due to adiabaticexpansion inside the load-lock chamber during vacuum evacuation, thesubstrate temperature decrease can be held not greater than 0.3° C. ifthe capacity of the load-lock chamber is held not greater than 20 timesthe volume of the substrate. Hence, without using substrate temperatureadjusting means or the like, a process such as exposure process can beperformed to the substrate promptly after the same is introduced intothe process chamber. Therefore, the throughput of the apparatus isimproved significantly.

Preferred embodiments in this aspect of the present invention will bedescribed below, in conjunction with the drawings.

Embodiment 3

FIGS. 10A and 10B show a third embodiment of the present invention. Inthis embodiment, the invention is applied to an exposure apparatus. Itcomprises a process chamber 1 that accommodates therein a wafer exposureprocess unit, not shown, and a reduced pressure He ambience is createdand kept therein. The apparatus further comprises a wafer carrier (wafersupply unit) 3 which is disposed in the atmosphere. In this embodiment,the wafer carrier 3 is a FOUP system. A chamber auxiliary room 2 isconnected to the process chamber 1, and second conveying means 52 to bedescribed later is disposed in this chamber auxiliary room 2.

Disposed between the chamber auxiliary room 2 and the wafer supply unit3 is a load-lock chamber 4 for allowing transfer of a wafer betweendifference ambiences. The load-lock chamber 4 is communicated with theatmosphere and the chamber auxiliary room 2, respectively, through afirst gate valve 41 and a second gate valve 42, respectively.

At the atmosphere side, there is first wafer conveying means 51 forconveying a wafer between the wafer carrier 3 and the load-lock chamber4. Inside the chamber auxiliary room 2, there is second wafer conveyingmeans 52 for conveying a wafer between the load-lock chamber 4 and awafer processing unit, not shown. Disposed between the wafer carrier 3in the atmosphere and the load-lock chamber 4, there is a caddy station6 in which a wafer can be stored into a caddy 7.

Around the first wafer conveying means 51 and the caddy station 6, thereis a mini clean booth 8. This clean booth 8 is structured to enclose thewhole of wafer conveying unit in the atmosphere. In this connection, theload-lock chamber 4 has an atmosphere side opening which opens to theinside of the clean booth 8. Also, as regards the wafer carrier 3, theFOPU system is attached to the wall of the clean booth 8 and thus theopening of the FOUP system faces the clean booth 8.

The first wafer conveying means 51 is structured to be able to accessevery one of load-lock chamber 4, wafer carrier 3 and caddy station 6.Specifically, in this embodiment, the load-lock chamber 4, the wafercarrier 3 and the caddy station 6 are disposed along a circumference,and a scalar robot is provided approximately at the center of thecircle.

The caddy station 6 has a wafer elevating mechanism 63 for assistingstoring a wafer on the first wafer conveying means into the caddy 7.

The caddy 7 has a structure such as shown in FIG. 11. The caddy 7includes a main frame 71 having three pins 72 formed on the top surfacethereof, and a wafer is to be placed on these pins. The bottom of themain frame 71 has a concaved shape so that a hand of the conveying meanscan be received and held there. The three pins 72 has a length slightlylonger than the amount of flexure of a wafer to be caused by the weightof the wafer itself as the same is placed on the pins, so as to preventcontact of the wafer held thereon with the base bottom face and also toassure a smallest space capacity.

The three pins 72 are provided on a base 74. The base 74 is mountedinside the caddy main frame 71, and it is made movable upwardly anddownwardly relative to the caddy main frame. The three pins 72 extendthrough bores formed in the top of the caddy frame 71 to hold a waferupon the caddy main frame 71. The clearance between each throughbore ofthe caddy main frame 71 and the pin 72 is gas-tightly sealed by sealmeans such as O-ring, for example.

A caddy cover 75 is openably and closably held by the caddy main frame71. The surface of the caddy cover 75, facing the caddy main frame 71,is formed with a concaved shape of a size that can accommodate a wafer.Furthermore, the caddy cover 75 has appropriate bores formed therein toallow passage of gasses therethrough, and each bore is provided with afilter 73 equivalent to ULPA. Preferably, the bores of the caddy cover75 should be formed at peripheral positions, stepping aside the waferunderneath.

FIG. 12 shows an example of the structure of the caddy station 6. Thecaddy station 6 comprises a main frame 61, a caddy mounting table 62 andwafer elevating means 63.

The caddy mounting table 62 is provided to hold a caddy at apredetermined position when a wafer is to be stored therein or to betaken out therefrom. It comprises three pins on which a caddy can beplaced. These pins may have a structure for holding a caddy byattraction. Furthermore, the caddy mounting table may be provided withpositioning pins for positioning a caddy or drift preventing pins foravoiding displacement of the caddy when a wafer is stored into or pulledfrom the caddy. In the drawing, a simplest structure only havingmounting pins is illustrated.

The wafer elevating mechanism 63 is made movable in upward and downwarddirections. Regarding a guide and a drive source for the movement, forexample, any known structure may be used. In the drawing, a simplestexample using upwardly and downwardly movable pins is illustrated.

As a caddy is placed on the caddy mounting table 62, the pins of thewafer elevating mechanism 63 are opposed to the base 74 of the caddy. Asthe wafer elevating mechanism 63 moves upwardly, the pins engage withthe bottom face of the base 74. With further upward motion of theelevating mechanism 63, the base 74 moves upwardly relative to the caddymain frame 71.

A wafer can be stored into the caddy 7 in the manner as shown in FIG.13.

Initially, the first wafer conveying means 51 having a wafer heldthereon stretches its arm out to convey the wafer up to a predeterminedposition above the caddy station 6. Subsequently, the wafer elevatingmechanism 63 of the caddy station 6 moves upwardly to raise the base 74of the caddy 7. With this motion, the pins 72 mounted on the base 74move upwardly and they are brought into engagement with the wafer on thehand. With further upward motion of the pins, the wafer is lifted awayfrom the hand of the first conveying means 51.

The first conveying means 51 retracts its arm and the hand is withdrawn,and then the wafer elevating mechanism 63 moves downwardly while holdingthe wafer thereon. The wafer moves downwardly with this motion. As thebase 74 of the caddy is lowered to a predetermined position of the caddymain frame 71, the wafer elevating means 63 moves away from the base 74,and it continues downward motion and finally it is retracted.

After the wafer is placed on the wafer mounting pins 72 of the caddy 7and the wafer elevating means 63 is retracted, the caddy cover 75 isclosed.

With the sequences described above, the procedure for storing a waferinto a caddy is completed.

Next, the wafer conveying operation in an exposure apparatus accordingto this embodiment of the present invention will be described.

The first conveying means 51 enters a wafer carrier 3 placed in theatmosphere, and it takes one wafer out of the carrier. The firstconveying means 51 now carrying one wafer thereon retracts its arm, andthe state of the caddy station 6 as well as the state of a caddy 7 uponthe caddy station are checked.

If the caddy 7 is ready for receiving a wafer, the first wafer conveyingmeans 51 turns its arm toward the caddy 7 and then stores the wafer intothe caddy 7 in the manner described hereinbefore.

After the wafer is stored into the caddy 7, the first wafer conveyingmeans 51 enters the caddy station 6 once more. Here, the hand of thefirst wafer conveying means 51 is arranged to hold both of a wafersingly and a caddy.

Specifically, the first wafer conveying means 51 enters the caddystation, with its position kept lower than the position thereof when itstored one wafer into the caddy 7 a little while ago and, also, lowerthan the bottom face of the caddy 7. After the hand approaches tounderneath the caddy 7, the first wafer conveying means 51 movesupwardly to lift the caddy 7 from the caddy station 6.

While holding the caddy 7 thereon, the first wafer conveying means 51retracts its arm. Then, the ambience of the load-lock chamber 4 ischecked.

If the load-lock chamber 4 is filled with an atmospheric ambience atthis time, the caddy 7 is loaded into the load-lock chamber inaccordance with the sequences illustrated in FIG. 14. The firstconveying means 51 rotates and turns its arm toward the load-lockchamber 4. After checking the open state of the gate valve 41, the firstconveying means stretches the arm out and it conveys the caddy 7 havinga wafer held thereon into the load-lock chamber 4.

Subsequently, the first wafer conveying means 51 moves its armdownwardly. Thus, the mount portion of the caddy 7 engages with thebottom of the load-lock chamber 4, and the caddy is mounted there. Evenafter the caddy 7 is mounted in the load-lock chamber 4, the first waferconveying means 51 continues the motion for lowering its arm and, as thearm moves away from the bottom of the caddy 7 and it reaches a positionenabling arm retraction, the downward motion is stopped.

Thereafter, the first wafer conveying means 51 draws its arm to retractthe hand from the load-lock chamber 4. After the wafer conveying means 1is retracted, the interface with the atmosphere is intercepted by thefirst gate valve 41 and ambience replacement is carried outsubsequently.

The ambience replacement can be done as follows.

After the first gate valve 41 is closed, a vacuum exhaust valve (notshown) is opened and, then, exhausting of the gas inside the load-lockchamber 4 is initiated by use of vacuum exhausting means (not shown). Asthe gas is exhausted and a predetermined vacuum level is reached, thevacuum exhaust valve is closed and, thus, the exhausting is completed.

Subsequently, He gas the same as the inside ambience gas of the processchamber 1 is supplied into the load-lock chamber 4, by opening a gassupply valve of gas supplying means (not shown). When a reduced pressureHe ambience approximately at the same pressure level as of the processchamber 1 is created inside the load-lock chamber 4, the gas supplyvalve is closed and the supply of He gas is turned off.

Here, the pressure is compared between the process chamber 1 and theload-lock chamber 4. If a pressure difference between these chambers islarger than a predetermined value, a pressure correcting operation iscarried out. Depending on the apparatus structure, the pressurecorrecting operation can be performed in various manners.

One example is that a communication pipe is provided between the processchamber 1 and the load-lock chamber 4, and a cutoff valve is provided ina portion of the pipe. When the pressure difference between the processchamber 1 and the load-lock chamber 4 is larger than a predeterminedvalue, the cutoff valve in the communication pipe is opened to providefluid communication between the process chamber 1 and the load-lockchamber 4. Basically the pressure difference can be removed by this, andthe ambience replacement operation for the load-lock chamber 4 is thusfinished.

Another method is that vacuum evacuation or ambience gas supply for theload-lock chamber 4 is carried out again, to produce a predeterminedpressure. More specifically, if the pressure of the load-lock chamber 4is higher than that of the process chamber 1, the vacuum exhaust valveis opened to perform vacuum evacuation. As a predetermined pressurelevel is reached, the vacuum exhaust valve is closed, and exhausting isstopped. If on the other hand the pressure inside the load-lock chamberis lower than the process chamber pressure, the He gas supply valve isopened to supply He gas until a predetermined pressure level is reached.As the pressure difference becomes smaller than the predetermined valueas a result of gas exhausting or gas supplying, the ambience replacementoperation for the load-lock chamber 4 is completed.

After the ambience replacement of the load-lock chamber 4 is finished,the second gate valve 42 is opened, and the second conveying means 52enters the load-lock chamber 4 to unload the caddy 7 out of theload-lock chamber 4 in accordance with the sequences inverse to theloading sequences.

The second wafer conveying means 52 conveys the caddy 7 onto a caddystation (not shown) inside the process chamber 1. At the caddy stationwithin the process chamber 1, the wafer is taken out from the caddy 7 inaccordance with the sequences inverse to those made at the caddy station6 in the atmosphere. Thus, the wafer is held by the second waferconveying means 52 and is conveyed onto the process station.

At this stage, the wafer temperature has already reached a predeterminedtemperature. Hence, a subsequent wafer process can be initiatedpromptly.

In this embodiment, since a wafer is stored in a caddy 7, there is nopossibility of particle adhesion during wafer loading and unloading ofthe load-lock chamber 4. This is a notable advantage because,conventionally, ambience replacement of a load-lock chamber involves aproblem of particle adhesion. More particularly, due to the flow of gasduring substrate loading and unloading, particles being present on thefloor or side wall surface of the load-lock chamber are scattered andthey are adhered to the wafer surface.

There is another problem that, while moisture content of the gas isfrozen by cooling of the gas during exhausting, fine particles containedin the gas as well are collected by this freezing into large-sizeparticles and adhered to the wafer.

In accordance with this embodiment of the present invention, as comparedtherewith, since the wafer is kept stored in a caddy 7 and, during thevacuum exhausting, only the gas inside the caddy is exhausted outwardlyof the caddy, the wafer is not exposed to the gas inside the load-lockchamber. In the gas supply, on the other hand, since a filter isprovided at the gas flow port of the caddy, any particles scatteredinside the load-lock chamber 4 can be caught by this filter, and they donot enter the caddy. With this arrangement, therefore, even if particlesare scattered during gas supply or gas exhaust of the load-lock chamber4, adhesion of particles onto the wafer can be prevented effectively.

Although many proposals have been made to avoid particle adhesion duringsubstrate loading and unloading of the load-lock chamber, such ascontrolling gas supply or gas exhaust, for example, this embodiment canbe free from particle adhesion without relying on any of them.

Embodiment 4

FIG. 15 shows an example of a structure according to a fourth embodimentof the present invention, and FIG. 16 illustrates the operationaccording to this embodiment.

In this embodiment, a caddy-like structure for accommodating a wafertherein is provided inside a load-lock chamber 4. On the other hand, inthe atmosphere, there are a wafer carrier (wafer supply unit) 3 andfirst wafer conveying means 51 for conveying a wafer between the wafercarrier 3 and the load-lock chamber 4. There is no caddy station as ofthe third embodiment. The remaining portion of this embodiment isessentially the same as the third embodiment.

The caddy-like structure 9 is disposed inside the load-lock chamber 4,and it is made movable from the load-lock chamber 4 to the atmosphereside and the process chamber side, respectively, through a first gatevalve 41 and a second gate valve 42, respectively, while being supportedby a sliding mechanism 96. The caddy-like structure 9 has an openableand closable cover 95 at the top thereof.

Disposed at the sides of the load-lock chamber 4, that is, at theatmosphere side and the process chamber side, are a first waferelevating mechanism 98 and a second wafer elevating mechanism 99. Thebasic caddy structure of the other portion is essentially the same as ofthe third embodiment.

In FIG. 16, a wafer is stored into the caddy-like structure 9 asfollows.

While the load-lock chamber 4 is kept open to the atmosphere, theatmosphere-side first gate valve 41 is opened. The caddy-like structure9 moves outwardly of the load-lock chamber 4 while being supported bythe sliding mechanism 96, and the cover 95 is opened. Then, the firstwafer conveying means 51 having a wafer held thereon stretches its armout to convey the wafer up to a predetermined position above thecaddy-like structure 9.

Subsequently, the first wafer elevating mechanism 98 of the caddy-likestructure 9 moves upwardly, to lift a wafer mounting portion 92 of thecaddy-like structure together with a base 94. The thus lifted wafermounting portion 92 raises the wafer off the hand of the first waferconveying means 51. As the first wafer conveying means 51 retracts itsarm and withdraw its hand, the first wafer elevating mechanism 98 movesdownwardly. With this motion, the wafer mounting portion 92 is loweredwhile the wafer is held thereon. With this motion, the wafer as well islowered and, when the wafer mounting portion 92 engages the caddy mainframe 91 and stops there, the wafer elevating mechanism 92 moves awayfrom the wafer mounting portion 92, and it continues downward motion andfinally it is retracted.

As the wafer elevating mechanism 98 is withdrawn, the cover 95 of thecaddy-like structure 9 is closed. After this, the caddy-like structure 9moves into the load-lock chamber 4 while being supported by the slidingmechanism 96, and then the first gate valve 41 is closed.

With the sequences described above, the procedure for loading a waferinto the caddy-like structure 9 is completed.

A wafer can be unloaded from the caddy-like structure 9 as follows.

Initially, whether the pressure difference between the load-lock chamber4 and the process chamber is not greater than a predetermined value ischecked and, if it is confirmed, the second gate valve 42 between theprocess chamber 1 and the load-lock chamber 4 is opened. Then, thecaddy-like structure 9 moves outwardly of the load-lock chamber 4 whilebeing supported by the sliding mechanism 96, and the cover 95 is opened.Subsequently, the second wafer elevating mechanism 99 of the caddy-likestructure 9 moves upwardly to lift the wafer mounting portion 92 of thecaddy-like structure as well as the wafer thereon, together with thebase 94.

Then, the second wafer conveying means 51 stretches its arm out, and thehand thereof approaches to a predetermined position below the wafer. Thesecond wafer elevating mechanism 99 moved downwardly and the wafer isplaced on the hand of the second wafer conveying means 52. Then, thewafer mounting portion 92 moves away from the wafer, and it is loweredtogether with the second wafer elevating mechanism 99, and is retracted.The second wafer conveying means 52 having a wafer placed on its handthen conveys the wafer onto the process station, not shown.

Next, the wafer conveying operation in an exposure apparatus accordingto this embodiment of the present invention will be described.

The first conveying means 51 enters a wafer carrier 3 placed in theatmosphere, and it takes one wafer out of the carrier. The firstconveying means 51 now carrying one wafer thereon retracts its arm, andthe state of the load-lock chamber 4 and the caddy-like structure 9 ischecked.

If the load-lock chamber 4 has an atmospheric inside ambience and thecaddy-like structure 9 is ready for receiving a wafer, the first waferconveying means 51 turns its arm toward the load-lock chamber 4 and thenstores the wafer into the caddy-like structure 9 in the manner describedhereinbefore.

After the wafer is stored into the caddy-like structure 9, the firstgate valve 41 is closed and then the ambience replacement of theload-lock chamber is carried out.

The ambience replacement can be done as follows.

After the first gate valve 41 is closed, a vacuum exhaust valve (notshown) is opened and, then, exhausting of the gas inside the load-lockchamber 4 is initiated by use of vacuum exhausting means (not shown). Asthe gas is exhausted and a predetermined vacuum level is reached, thevacuum exhaust valve is closed and, thus, the exhausting is finished.

Subsequently, He gas the same as the inside ambience gas of the processchamber 1 is supplied into the load-lock chamber 4, by opening a gassupply valve of gas supplying means (not shown). When a reduced pressureHe ambience approximately at the same pressure level as of the processchamber 1 is created inside the load-lock chamber 4, the gas supplyvalve is closed and the supply of He gas is turned off.

Here, the pressure is compared between the process chamber 1 and theload-lock chamber 4. If a pressure difference between these chambers islarger than a predetermined value, a pressure correcting operation iscarried out. Depending on the apparatus structure, the pressurecorrecting operation can be performed in various manners.

One example is that a communication pipe is provided between the processchamber 1 and the load-lock chamber 4, and a cutoff valve is provided ina portion of the pipe. When the pressure difference between the processchamber 1 and the load-lock chamber 4 is larger than a predeterminedvalue, the cutoff valve in the communication pipe is opened to providefluid communication between the process chamber 1 and the load-lockchamber 4. Basically the pressure difference can be removed by this, andthe ambience replacement operation for the load-lock chamber 4 is thusfinished.

Another method is that vacuum evacuation or ambience gas supply for theload-lock chamber 4 is carried out again, to produce a predeterminedpressure. More specifically, if the pressure of the load-lock chamber 4is higher than that of the process chamber 1, the vacuum exhaust valveis opened to perform vacuum evacuation. As a predetermined pressurelevel is reached, the vacuum exhaust valve is closed, and exhausting isstopped. If on the other hand the pressure inside the load-lock chamberis lower than the process chamber pressure, the He gas supply valve isopened to supply He gas until a predetermined pressure level is reached.As the pressure difference becomes smaller than the predetermined valueas a result of gas exhausting or gas supplying, the ambience replacementoperation for the load-lock chamber 4 is completed.

After the ambience replacement of the load-lock chamber 4 is finished,the second gate valve 42 is opened, and the second conveying means 52unloads the wafer out of the caddy-like structure 9 in the mannerdescribed hereinbefore, and the wafer is conveyed onto the processstation, not shown.

At this stage, the wafer temperature has already reached a predeterminedtemperature. Hence, a subsequent wafer process can be initiatedpromptly.

Embodiment 5

FIG. 17 illustrates a fifth embodiment of the present invention. In thisembodiment, a load-lock chamber 4 is structured to provide a variableinside capacity. The remaining portion of this embodiment has a similarstructure as of the fourth embodiment.

When the first wafer conveying means 51 or the second wafer conveyingmeans 52 enters the load-lock chamber 4 while holding a wafer thereon,it should approach while keeping its height higher than the level of thewafer holding portion inside the load-lock chamber 4. Thus, in thiscase, the height of the ceiling of the load-lock chamber 4 should besufficiently large as compared with the height D1.

However, in order to make the load-lock chamber capacity a few timeslarger than the wafer volume, the height of the ceiling should be madenot greater than D2 and, thus, generally D1>D2.

In consideration of it, in this embodiment, the ceiling of the load-lockchamber 4 is made movable in upward and downward directions. Simply, theceiling may be provided with a piston-like structure.

Next, referring to FIG. 17, the wafer conveying operation in an exposureapparatus according to this embodiment of the present invention will bedescribed.

The first conveying means 51 enters a wafer carrier 3 placed in theatmosphere, and it takes one wafer out of the carrier. The firstconveying means 51 now carrying one wafer thereon retracts its arm, andthe state of the load-lock chamber 4 is checked.

If the load-lock chamber 4 has an atmospheric inside ambience and thedistance between the ceiling and the floor of the load-lock chamber 4 isnot less than D1, the first wafer conveying means 51 turns its armtoward the load-lock chamber 4. After checking that the first gate valve41 is open, it stretches the arm and loads the wafer into the load-lockchamber 4.

Subsequently, the first wafer conveying means 51 moves its armdownwardly. The wafer is moved onto the wafer mounting portion insidethe load-lock chamber 4. The arm further moves downwardly and, as thehand disengages from the wafer bottom face and it reaches a positionenabling hand retraction, the downward motion is stopped.

Thereafter, the first wafer conveying means 51 draws its arm to retractthe hand from the load-lock chamber 4. After the hand is retracted fromthe load-lock chamber 4, then the load-lock chamber capacity reducingoperation is carried out. Namely, while the first gate valve 41 is keptopen, the ceiling of the load-lock chamber 4 having a piston-likestructure gradually moves downwardly and, when the distance to the floorof the load-lock chamber becomes equal to D2, the motion is stopped.

After changing the load-lock chamber capacity described above, thecommunication with the atmosphere is intercepted by the first gate valve41 and, then, the ambience replacement is carried out.

The ambience replacement can be done as follows.

After the first gate valve 41 is closed, a vacuum exhaust valve (notshown) is opened and, then, exhausting of the gas inside the load-lockchamber 4 is initiated by use of vacuum exhausting means (not shown). Asthe gas is exhausted and a predetermined vacuum level is reached, thevacuum exhaust valve is closed and, thus, the exhausting is completed.

Subsequently, He gas the same as the inside ambience gas of the processchamber 1 is supplied into the load-lock chamber 4, by opening a gassupply valve of gas supplying means (not shown). When a reduced pressureHe ambience approximately at the same pressure level as of the processchamber 1 is created inside the load-lock chamber 4, the gas supplyvalve is closed and the supply of He gas is turned off.

Here, the pressure is compared between the process chamber 1 and theload-lock chamber 4. If a pressure difference between these chambers islarger than a predetermined value, a pressure correcting operation iscarried out. Depending on the apparatus structure, the pressurecorrecting operation can be performed in various manners.

One example is that a communication pipe is provided between the processchamber 1 and the load-lock chamber 4, and a cutoff valve is provided ina portion of the pipe. When the pressure difference between the processchamber 1 and the load-lock chamber 4 is larger than a predeterminedvalue, the cutoff valve in the communication pipe is opened to providefluid communication between the process chamber 1 and the load-lockchamber 4. Basically the pressure difference can be removed by this, andthe ambience replacement operation for the load-lock chamber 4 is thusfinished.

Another method is that vacuum evacuation or ambience gas supply for theload-lock chamber 4 is carried out again, to produce a predeterminedpressure. More specifically, if the pressure of the load-lock chamber 4is higher than that of the process chamber 1, the vacuum exhaust valveis opened to perform vacuum evacuation. As a predetermined pressurelevel is reached, the vacuum exhaust valve is closed, and exhausting isstopped. If on the other hand the pressure inside the load-lock chamberis lower than the process chamber pressure, the He gas supply valve isopened to supply He gas until a predetermined pressure level is reached.As the pressure difference becomes smaller than the predetermined valueas a result of gas exhausting or gas supplying, the ambience replacementoperation for the load-lock chamber 4 is completed.

After the ambience replacement of the load-lock chamber 4 is finished,the second gate valve 42 is opened. As the second gate valve 42 isopened and the load-lock chamber 4 is communicated with the processchamber 1, the ceiling of the load-lock chamber 4 starts upward motion.As the distance between the ceiling and the floor surface becomes equalto D2, the motion is stopped.

Subsequently, the second conveying means 52 enters the load-lock chamber4 to unload the wafer out of the load-lock chamber 4. The second waferconveying means 52 holds the wafer and conveys it onto a processstation, not shown.

At this stage, the wafer temperature has already reached a predeterminedtemperature. Hence, a subsequent wafer process can be initiatedpromptly.

This embodiment may be modified as follows.

Namely, as shown in FIG. 18, the wafer mounting portion of the load-lockchamber 4 may made movable upwardly and downwardly. For wafer loadingand unloading, the wafer mounting portion is raised to allow transfer ofthe wafer between the first wafer conveying means 51 and the secondwafer conveying means 52. After receiving the wafer, the wafer mountingportion is lowered. Here, the wafer mounting portion moves downwardly upto its lowest position where the wafer is still kept out of contact withthe floor of the load-lock chamber. Thereafter, the ceiling of theload-lock chamber 4 moves downwardly until the distance to the load-lockchamber floor becomes equal to or less than D2. Here, the ceiling of theload-lock chamber 4 is lowered up to its lowest position where it isstill kept out of contact with the wafer top face.

Operations such as ambience replacement operation may be performedessentially in the same manner as has been described hereinbefore.

As described, with the structure that the wafer mounting portion insidethe load-lock chamber 4 is made movable up and down, the capacity of theload-lock chamber 4 can be made much smaller and, hence, the temperaturedecrease of the wafer due to adiabatic expansion during vacuumevacuation can be reduced.

Embodiment 6

A sixth embodiment of the present invention will now be described. Thisembodiment has a similar structure as the fifth embodiment, and theload-lock chamber is arranged to provide a variable inside capacity.

Next, referring to FIG. 19, the wafer conveying operation in an exposureapparatus according to this embodiment of the present invention will bedescribed.

The first conveying means 51 enters a wafer carrier 3 placed in theatmosphere, and it takes one wafer out of the carrier. The firstconveying means 51 now carrying one wafer thereon retracts its arm, andthe state of the load-lock chamber 4 is checked.

If the load-lock chamber 4 has an atmospheric inside ambience and thedistance between the ceiling and the floor of the load-lock chamber 4 isnot less than D1, the first wafer conveying means 51 turns its armtoward the load-lock chamber 4. After checking that the first gate valve41 is open, it stretches the arm and loads the wafer into the load-lockchamber 4.

Subsequently, the first wafer conveying means 51 moves its armdownwardly. The wafer is moved onto the wafer mounting portion insidethe load-lock chamber 4. The arm further moves downwardly and, as thehand disengages from the wafer bottom face and it reaches a positionenabling hand retraction, the downward motion is stopped.

Thereafter, the first wafer conveying means 51 draws its arm to retractthe hand from the load-lock chamber 4. After the hand is retracted fromthe load-lock chamber 4, then the load-lock chamber capacity reducingoperation is carried out. Namely, while the first gate valve 41 is keptopen, the ceiling of the load-lock chamber 4 having a piston-likestructure gradually moves downwardly and, when the distance to the floorof the load-lock chamber becomes equal to D2, the motion is stopped.

After changing the load-lock chamber capacity described above, thecommunication with the atmosphere is intercepted by the first gate valve41 and, then, the ambience replacement is carried out.

The ambience replacement can be done as follows.

After the gate valve is closed, a vacuum exhaust valve (not shown) isopened and, then, exhausting of the gas inside the load-lock chamber 4is initiated by use of vacuum exhausting means (not shown). As the gasis exhausted and a predetermined vacuum level is reached, the vacuumexhaust valve 43 is closed and, thus, the exhausting is completed.

Subsequently, He gas the same as the inside ambience gas of the processchamber 1 is supplied into the load-lock chamber 4, by opening a gassupply valve of gas supplying means (not shown). Here, simultaneouslywith the gas supply, the ceiling of the load-lock chamber 4 is movedupwardly to increase the capacity of the load-lock chamber. The upwardmotion of the load-lock chamber ceiling continues until the distancebetween the ceiling and the chamber floor becomes equal to D2 and, atthe moment as D2 is reached, the upward motion is stopped.

Where the capacity of the load-lock chamber is enlarged by moving thechamber ceiling upwardly in a certain ambience different from vacuum,the gas is cooled by adiabatic expansion. However, since in this casethe gas supply is carried out concurrently, the gas temperature wouldnot decrease. Hence, the problem of wafer temperature decrease does notoccur.

When a reduced pressure He ambience approximately at the same pressurelevel as of the process chamber 1 is created inside the load-lockchamber 4, the gas supply valve is closed and the supply of He gas isturned off.

Among the above-described operations, upward motion of the ceilingshould desirably be performed and completed before the He gas issupplied to a predetermined pressure.

If the He gas pressure exceeds the predetermined pressure before thedistance between the chamber ceiling and the chamber floor reaches D2and thus the He gas supply is turned off, the ambience pressure insidethe load-lock chamber 4 may desirably be checked after the upward motionof the ceiling is completed and, if it is lower than the predeterminedpressure, the He gas may be supplied again.

Subsequently, the pressure is compared between the process chamber 1 andthe load-lock chamber 4. If a pressure difference between these chambersis larger than a predetermined value, a pressure correcting operation iscarried out. Depending on the apparatus structure, the pressurecorrecting operation can be performed in various manners.

One example is that a communication pipe is provided between the processchamber 1 and the load-lock chamber 4, and a cutoff valve is provided ina portion of the pipe. When the pressure difference between the processchamber 1 and the load-lock chamber 4 is larger than a predeterminedvalue, the cutoff valve in the communication pipe is opened to providefluid communication between the process chamber 1 and the load-lockchamber 4. Basically the pressure difference can be removed by this, andthe ambience replacement operation for the load-lock chamber 4 is thusfinished.

Another method is that vacuum evacuation or ambience gas supply for theload-lock chamber 4 is carried out again, to produce a predeterminedpressure. More specifically, if the pressure of the load-lock chamber 4is higher than that of the process chamber 1, the vacuum exhaust valveis opened to perform vacuum evacuation. As a predetermined pressurelevel is reached, the vacuum exhaust valve is closed, and exhausting isstopped. If on the other hand the pressure inside the load-lock chamberis lower than the process chamber pressure, the He gas supply valve isopened to supply He gas until a predetermined pressure level is reached.As the pressure difference becomes smaller than the predetermined valueas a result of gas exhausting or gas supplying, the ambience replacementoperation for the load-lock chamber 4 is completed.

After the ambience replacement of the load-lock chamber 4 is finished,the second gate valve 42 is opened. As the second gate valve 42 isopened and the load-lock chamber 4 is communicated with the processchamber, the second conveying means 52 enters the load-lock chamber 4 tounload the wafer out of the load-lock chamber 4. The second waferconveying means 52 holds the wafer and conveys it onto a processstation, not shown.

At this stage, the wafer temperature has already reached a predeterminedtemperature. Hence, a subsequent wafer process can be initiatedpromptly.

It should be noted there that the present invention is not limited tosubstrate processing apparatuses or substrate conveying methodsdescribed above. For example, a substrate processing apparatus accordingto the invention may be one having a first process chamber forperforming a process to an object to be processed, in an ambiencedifferent from an atmosphere, a second process chamber connected to thefirst process chamber and the atmosphere, respectively, through anopening/closing mechanism, and conveying means for conveying the objectfrom the atmosphere to the first process chamber through the secondprocess chamber, wherein the capacity of the second process chamber isapproximately not greater than 10 times the volume of the object.

Furthermore, as described with reference to some embodiments, theinvention is applicable to an exposure apparatus having such substrateprocessing apparatus. More specifically, such an exposure apparatus mayinclude a substrate processing apparatus as described and an opticalsystem for directing light from a light source to the object to beprocessed. More preferably, the apparatus may further comprise anillumination optical system, a reticle stage for supporting a reticle tobe illuminated by the illumination optical system, and a projectionoptical system for projecting light from the reticle to the object to beprocessed.

Furthermore, the present invention is applicable also to a devicemanufacturing method that uses an exposure apparatus such as describedabove. Preferably, the method may include a step of exposing a substrateto be processed, by use of an exposure apparatus as described above, anda step of developing the exposed substrate.

In accordance with some preferred embodiments of the present inventiondescribed hereinbefore, a wafer loaded into a processing apparatus byway of a load-lock chamber has reached a predetermined temperature atthe moment as the same is loaded. Hence, a subsequent process such asexposure process can be initiated promptly, and the throughput of theapparatus can be improved significantly.

While the invention has been described with reference to the structuresdisclosed herein, it is not confined to the details set forth and thisapplication is intended to cover such modifications or changes as maycome within the purposes of the improvements or the scope of thefollowing claims.

This application claims priority from Japanese Patent Application No.2003-402488 filed Dec. 2, 2003, for which is hereby incorporated byreference.

1. A load-lock system, comprising: a chamber housing; and a capacitychanging system for changing the capacity of said chamber housing.
 2. Aload-lock system according to claim 1, wherein said capacity changingsystem includes a driving unit for moving a predetermined portion ofsaid chamber housing.
 3. A load-lock system according to claim 2,wherein said predetermined portion of said chamber housing includes atable for supporting an object.
 4. A load-lock system according to claim1 further comprising a seal member for sealing between a predeterminedportion of said chamber housing and another portion of said chamberhousing.
 5. A load-lock system according to claim 2, further comprisinga seal member for sealing between said predetermined portion of saidchamber housing and another portion of said chamber housing.
 6. Aload-lock system according to claim 1, further comprising a tubularmember provided to reduce a pressure inside said chamber housing.
 7. Aload-lock system according to claim 6, further comprising a valvethrough which said tubular member is connected to a main chamber inwhich the object is to be processed.
 8. A load-lock system according toclaim 6, further valve and an exhaust pump, wherein said tubular memberis connected to said exhaust pump through said valve.
 9. A devicemanufacturing apparatus including a load-lock system as recited inclaim
 1. 10. An exposure apparatus for exposing an object to a patternradiation, including a load-lock system as recited in claim
 1. 11. Adevice manufacturing method, comprising the steps of: exposing an objectto a pattern radiation by use of an exposure apparatus as recited inclaim 10; and developing the exposed object.
 12. A load-lock method,comprising the steps of: conveying an object into a chamber housing;reducing the capacity of the chamber housing after said conveying step;and reducing the pressure inside the chamber housing after said capacityreducing step.
 13. A method according to claim 12, wherein, in saidcapacity reducing step, a predetermined portion of the chamber housingis moved.
 14. A method according to claim 13, wherein the predeterminedpotion of the chamber housing includes a table for supporting theobject.
 15. A method according to claim 13, wherein an interface betweenthe predetermined portion of the chamber housing and another portion ofthe chamber housing is sealed.
 16. A method according to claim 13,wherein, in said pressure reducing step, the pressure is reduced by useof a tubular member.
 17. A method according to claim 16, wherein, forthe pressure reduction, the tubular member is connected to a mainchamber in which the object is to be processed.
 18. A method accordingto claim 16, wherein, for the pressure reduction, the tubular member isconnected to an exhaust pump.